title: Echocardiographic optimization of the atrioventricular and interventricular intervals during cardiac resynchronization.
abstract: An optimized atrioventricular (AV) interval can maximize the benefits of cardiac resynchronization therapy (CRT). If programmed poorly, it may curtail beneficial effects of CRT. AV optimization will not convert non-responder to responder, but may convert under-responder to improved status. There are many echocardiographic techniques for AV optimization but there is no universally accepted gold standard. The optimal AV delay varies with time, necessitating periodic re-evaluation. As the optimal AV delay may lengthen on exercise, a rate-adaptive AV delay should not be routinely programmed. Intra- and interatrial conduction delays may require AV junctional ablation when AV optimization is impossible in patients with a poor clinical response. Fusion with the spontaneous QRS complex may be acceptable on a trial basis to seek a better clinical response or with a short PR interval. Routine VV optimization is presently controversial but programming may prove beneficial in some patients with a suboptimal CRT response where no cause is found. It may partially compensate for less than optimal left ventricular (LV) lead position and may correct for heterogeneous ventricular activation including a prolonged LV latency interval and slow conduction (scarring) near the LV pacing site. VV timing is generally programmed using the aortic velocity-time integral, and long-term variations of the optimal value necessitate periodic re-evaluation.
authors.affiliation: Cardiology Division, University of South Florida College of Medicine and Tampa General Hospital, Tampa, FL, USA. ssbarold@aol.com
authors.forename: S Serge
authors.initials: SS
authors.lastname: Barold
authors.forename: Arzu
authors.initials: A
authors.lastname: Ilercil
authors.forename: Bengt
authors.initials: B
authors.lastname: Herweg
mesh_terms: D002304:Cardiac Pacing, Artificial / Q000379:methods*; D004452:Echocardiography / Q000379:methods*; D006333:Heart Failure / Q000000981:diagnostic imaging* / Q000517:prevention & control*; D006801:Humans; D007089:Image Enhancement / Q000379:methods; D017063:Outcome Assessment, Health Care / Q000379:methods*; D011786:Quality Control; D016896:Treatment Outcome; D018084:Ultrasonography, Interventional / Q000379:methods*